Two stage dripolene hydrogenation



Jan. 3, 1967 L. c. DOELP ETAL 3,295,120

TWO STAGE DRIPOLENE HYDROGENATION Filed Sept. 30, 1963 2 Sheets-Sheet 1 INVENTORS.

Louis C. Doelp, Stanley Gussow 8 Thomas OMichue! ATTORNEY Jan. 3, 1967 L, c. DQELP ETAL 3,296,120

TWO STAGE DRIPOLENE HYDROGENATION Filed Sept. 50, 1963 2 Sheets-Sheet 2 INVENTORS.

Louis C. Doelp, Sronley Gussow 8 Thomas C. Michael ATTORNEY.

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United States Patent TWO STAGE DRHOLENE HYDROGENATION Louis C. Doelp, Glen Mills, Stanley Gussow, Broomall,

and Thomas C. Michael, Glenolden, Pa., assignors to Air Products and Chemicals, Inc., Philadelphia, Pa., a

corporation of Delaware Filed Sept. 30, 1963, Ser. No. 312,456 4 Claims. (Cl. 208-143) This invention relates to the catalytic hydrogenation of olefinic hydrocarbons and, more specifically, to the catalytic hydrogenation of pyrolysis condensates such as dripolene for motor gasoline or aromatics production.

Dripolene is the normally liquid mixture of hydrocarbons obtained as a byproduct in the production of ethylene during the high temperature pyrolysis of gaseous and/ or liquid hydrocarbons. A material which condenses out of the hydrocarbons when the pyrolysis products are rapidly cooled, e.g., by quenching, is a liquid known as dripolene, which generally boils between 75 to 500 F.

While suggestions have been made to send dripolene to aromatic extraction units for recovery of pure aromatics such as benzene, the material is unsuitable without further treatment for use in aromatics'production due to its high olefin content. Even the potential of dripolene as a blending stock for gasolines has not been realizable. Since dripolene contains materials such as olefins and diolefins which tend to form gum-like polymers, especially when heated, the quantity of dripolene blended into motor fuels has been relatively small.

Various suggestions directed to the selective hydrogenation of mono-olefins and/or diolefins, without simultaneously hydrogenating the aromatic compounds present in dripolene, have not been commercially satisfactory due to such problems as comparatively low conversion rates, excessive coke make and catalyst deactivation.

It is therefore, an object of the present invention to provide an improved method for the selective catalytic hydrogenation of olefinic hydrocarbons present in dripolene charge stocks.

It is another object of the present invention to provide a process for the selective catalytic hydrogenation of olefinic hydrocarbons present in dripolene without simultaneously hydrogenating aromatic compounds.

It is a further object of the invention to provide a method for the selective hydrogenation of dripolene to provide a blending stock [for motor gasolines.

It is still another object of the present invention to provide a process for the catalytic hydrogenation of dripolene which may be conducted for periods substantially in excess of those heretofore obtained.

In accordance with the present invention, the catalytic hydrogenation of dripolene charge stock is effected in at least one reaction zone by contacting a commingled stream of vaporized dripolene and a hydrogen-containing gas with sulfided cobalt molybdate under a carefully regulated set of conditions such as temperature, pressure, hydrogen to oil ratio and space rate. The hydrogenation is highly selective in two important aspects: (1) aromatics hydrogenation does not occure at any level of olefin hydrogenation and (2) appreciable hydrogena- 3,296,120 Patented Jan. 3, 1967 tion of monoolefins occurs only after diolefins have been completely hydrogenated to mono-olefins. Another desirable feature of the present invention, especiallywith respect to the preparation of a blending stock for motor gasolines, is the fact that hydrogenation of the charge stock results in a slight gain in the leaded octane rating and only a slight lowering of the clear octane number.

The catalyst employed in the practice of the present invention is an alumina-supported cobalt molybdate Which is in a sulfided state during it use. The catalyst may either be presulfided or, depending on the nature of the charge stock, permitted to attain its sulfided state during the initial startup of the operation. The catalyst contains a total of about 8 to 18% by weight of the oxides of the molybdenum and cobalt in the approximate weight ratio of about 4/1 to 5/1 (Moo /C00). The preferred catalysts are those containing at all times during use at least one atom of sulfur for each atom of cobalt and for each atom of molybdenum. Thus, for a cobalt molybdate catalyst which, prior to sulfidation, contains 15% M00 and 3% C00, the minimum sulfur content of the freshly sulfided catalyst will be about 7.9% by Weight. In the described operation, this catalyst is not subject to deactiviation by sulfur or nitrogen in the feed or hydrogen stream and, in fact, contributes to the removal of such contaminants by converting them into readily separable materials.

The conditions of temperature, pressure, liquid hourly space velocity and hydrogen-containing gas rate are interrelated. The temperature in the reaction zones is maintained between 300 to 900 F. and preferably between 400 and 800 F. Pressures from about up to 1,000 p.s.i.g. can be utilized with pressures from 400 to 800 p.s.i.g. being preferred. A liquid hourly space velocity (LHSV) of 0.1 to 20 may be employed with a preferred LHSV in the range of 1 to 5. The hydrogen-containing gas may be derived from a naphtha reforming operation, but, in any respect, is composed of at least 25% by volume hydrogen. The hydrogen is employed in a proportion of 500 to 10,000 standard cubic feet per barrel of dripolene charge stock and preferably in the amount of 1,000 to 7,000 standard cubic feet per barrel of charge stock.

The temperature of the charge stock in passing through each reaction zone rises because of the exothermic nature of the reaction to an outlet temperature above that of the inlet temperature but is not allowed to rise in excess of an outlet temperature of 900 F. The total vapor efiluent from the first and each intermediate reaction zone is immediately cooled to an appropriate lower temperature before being admitted to the next succeeding reaction zone wherein the reactants again contact catalyst. Within the operating temperature range, the catalyst cycle life has been projected to be greater than 6 months.

Since the catalyst is deactivated when excessive temperatures are encountered, the inlet temperature of the vation produced in the reaction. Ordinarily, under the.

preferred range of operating conditions, the inlet temperature will be above about 300 F. and preferably in the range of 400 to 600 F. In the reaction, it is desirable that the AT due to the exothermic nature of the reaction be contained within the range of 50 to 150 F. for eflicient operation and satisfactory results.

With continued operation over comparatively long periods, it may be desirable to raise the operating temperature to some extent. Periodic increases in temperature will primarily be dictated by the required properties of the unit liquid product.

In addition, the size of the several reaction zones or reactors of the series and the quantity of catalyst therein need not be equal. Accordingly, the temperature to which the products from a preceding reaction zone are cooled before admission to the next reaction zone will be governed by the extent of the expected temperature rise therein and consistent with achieving the desired product.

Under these conditions, the catalyst is maintained at a high catalytic activity level which is important not only from the standpoint of the immediate benefits in the yield of recovered valuable liquid product but also, and more importantly, from the standpoint of enhanced uninterrupted on-stream periods of operation.

The invention is clarified by reference to the following description read in connection with the drawings. FIG URES 1 and 2 are highly schematic illustrations of spe cific embodiments for dripolene hydrogenation.

' In FIGURE 1, dripolene is passed to a vaporizer either directly or indirectly. When the full dripolene charge stock is employed, valves 17 and 18 are closed and dripo lene from storage area is passed through lines 11 to 14 directlyto venturi device 15, which is attached to vaporizer 16.

As an alternative embodiment, a particular fraction may be separated from the dripolene charge stock in a feed splitter and sent to the vaporizer. In this second embodiment, valves 19 and 20 are closed and dripolene from storage area 10 is conveyed by lines '11 and 21 to feed-splitter 22. In the feed-splitter, a particular fraction, such as the 115 F. to bottoms or 150 F. to bottoms fraction, is separated from the charge stock and then transmitted to ven turi device through lines 23, 13, and 14. The lower boiling fraction from the feed-splitter is composed mainly of C hydrocarbons and is removed by line 24 for further separation and/ or recovery.

In either embodiment, the dripolene from storage area 10 is preferably raised to the desired operating pressure and may be heated to between 200 to 400 F. (by means not shown) prior to its introduction into vaporizer 16.

The dripolene charge stock supplied by line 13 may be blended with liquid from line 25, which has not vaporized in vaporizer 16. Generally, however, valve 26 is closed and charge stock from line 13 is passed through line 14 to venturi device 15, where it is mixed with hot (700 to 1100 F.) hydrogen-containing recycle gas from line 27. The cornmingled mixture of dripolene charge stock and hydrogen-containing gas is flashed in vaporizer 16 where about 0.2 to. 5% and generally 1 to 2% of the liquid re mains unvaporized. The excess accumulation of unvaporized charge is drawn oft through line 28 which is regulated by valve 29.

Vapor mixture passes from the vaporizer through line 30 and after any required adjustment in temperature enters the first reactor 31 where the mixture contacts sufided cobalt molybdate catalyst. The efliuent from the first reactor is then passed through line 32 into a cooling device 33 and thereafter transmitted by line 34 to the second reactor 35. The second reactor is operated in a manner essentially identical with that of the first reactor.

Reactor effiuent from the second reactor is heat exchanged With recycle gas in heat exchanger 37 and then cooled to about 80 F. in a second heat exchanger 39, after passing through lines 36 and 38, respectively. The cold reactor efiluent is passed through line 40 to a gasliquid separator 41. Gas escapes from the separator through line 42 and together with added makeup hydrogen from source 43 (and line 44) moves through line 45 to recycle pump 46. The recycled hydrogen-containing gas, after passing through line 47 and heat exchanger 37, is then passed through line 48 and heater 49 to attain the required temperature before being sent back to venturi device 15 by line 27.

Liquid from the gas-liquid separator 41 is sent by line 50 to stabilizer 51. The overhead from the stabilizer ordinarily would pass through line 52 to a gas plant (not shown), while liquid is conveyed from the bottom of the stabilizer through line 53 to a rerun column and/or to gasoline storage (not shown). It a rerun column is em ployed the bottoms fraction may be recycled to the vaporizer by suitable means (not shown).

In the alternative procedure shown by FIGURE 2, dripolene charge stock from line after any desired adjustment with respect to pressure and temperature is sent directly to feed vaporizer 101. Hot hydrogen-containing gas from line 102 is employed to vaporize the dripolene charge stock. A desired amount of unvaporized charge material is maintained in the vaporizer while excess amounts (less than about 5% of the charge) are withdrawn through valved line 103.

The vapors from vaporizer 101 are then passed through line 104 and after any required adjustment in temperature enter a two-stage hydrogenation reactor 105, where the vapors contact sulfided cobalt molybdate catalyst.

In the production of a blending stock for motor gasolines, a liquid gasoline component, preferably free of diolefins, from line 106, is employed for a direct interstage quench to cool the vapors from the first stage of the reactor to about 50 to 150 F. below the outlet temperature before they enter the second stage. The reaction conditions in the second stage are similar to those employed in the first stage.

In the production of aromatics, other quenching agents may be employed such as the product itself.

The effluent from the two-stage hydrogenation reactor 105 is conveyed by lines 107 and 109 through a heat exchanger 108, and high-pressure condenser 110. The partially condensed material is then transmitted by line 111 to a high-pressure liquid gas separator 112, from which the liquid is sent by line 113 to a stabilizer (not shown) and all or part of the gas is recycled through line 114 to the hydrogen stream.

Makeup hydrogen from a reformer or another convenient source is supplied from line 115 to multistage compressor 116, wherein a mixture of makeup hydrogen and recycle gas is pressurized for use in vaporizer 101. The hydrogen-containing gas from compressor 116 is transmitted through line 117 to heat exchanger 108, where it is initially heated by the effluent from reactor 105. The gas thus heated is sent through line 118 for any further heating, if required, in heater 119 prior to introduction into vaporizer 101.

Example I A dripolene charge stock was analyzed by conventional techniques and found to have the following characteristics and composition:

TABLE 1 ASTM distillation range F.: Charge stock A 5 TABLE 1Continued ASTM distillation range F.: Charge stock A 80% 231 90% 257 95% 272 E.P. (end point) 293 DP. (dry point) 289 API gravity 44.6 Total nitrogen, p.p.m. 5 Bromine number 64.5

Bromine number (after maleic anhydride treat) 39.4 Molecular weight 85 TABLE 2 Chemical composition vol. percent of fraction Charge stock A Paraflins 10.2

Olefins 30.6 Naphthenes 8.2 Aromatics 5 1.0

To produce a stable motor gasoline, a mixture of hydrogen-containing gas and dripolene, having the characteristics and composition set forth for Charge Stock A, was contacted with sulfided cobalt molybdate catalyst, containing prior to sulfidation 15% M and 3% C00, in a reactor at the following conditions:

Under the aforementioned operating conditions, the initial charge stock was hydrogenated to a bromine number of 35 for product (a) and 47 for product (b). The products of this partial hydrogenation of the charge stock after distillation to an approximate 95 volume percent overhead had the characteristics shown in the following table.

TABLE 4 Charge Product Product Stock A A1? 1\f/zlral5vitz lrli .1 44. 6 46. 5 46. 5

'st' t n,

As IBP :i 127 128 130 50%-- 190 192 194 90%- 257 260 262 F-l Clear Octane Number 97.2 96. 5 96. 9

F-l +3 cc. TEL (Tetraethyllead) 100.4 102. 5 101.2

Existent Gnm, mg./100 ml. *n-Hexane Washed 68. 4 *0. 1 *0. 6

5 Hr. Potential Gum, Ing./100 ml 1, 800 0. 4 5. 7

16 Hr. Potential Gum, mg./100 ml 3,000 6. 8 7. 8

Gui Dish Glam, rug/1%) ml 1572 I In 2 t rS uctlon s a 090 022 040 N,Ndi-sec-butyLp-phenylene annne Inhibitor, #1, /000 bbls 0 5 10 Typical material balances of Product (a) and Product b) are set forth in Table 5.

TABLE 5 Charge Stock Product Product Bromine No 64.5 550 47. o Bromine N0. after M.A. Treat. 39. 4 35. 0 47. 0

Wt. Basis of Feed to Vaporizer: Prod Prod 0 100. 0 100. 0 Hydrogen 0. 4 0. 2

Total 100.4 100.2

0 0.1 0.1 04. U. 5 O. 4 05* Product 97. 8 97. 7 Btms 2. 0 2.0

Total 100. 4 100.2

Volume Basis:

05+ 100. 0 99. 9 99. 9 Btms 1.0 1.0

Total 100. 0 100.9 100.9

7%.?8109711; Composition of total P araflinsnn 10. 2 16.8 12.8 30. 6 16.6 25. 6 11. 3 9. 4 14. 5 5. 3 0. 0 14. 0 7. 2 11.1 8. 2 15. 6 10.6 51. 0 51.0 51. 0 27.0 27.0 27.0 16. 3 16. 3 16. 3 Xylenes. 7. 7 7. 7 7. 7 Hydrogen Consumed, S.c.f./bbl 197 117 Sulfur, wt. percent Chg 0.090 0. 022 0.040 Percent Desnlfm'imtirm 7 EXAMPLE II A dripolene charge stock was analyzed by conventional techniques and found to have the following character- Bromine number (after maleic anhydride [M.A.]

treatment) 48 Molecular weight TABLE 7 Chemical composition Charge stock vol. percent of traction: B

Paratfins 14.2 Olefins 26.4 Naphthenes 8.1 Aromatics 5 1.3

For aromatics production, a mixture of hydrogen-containing gas and dripolene, having the characteristics and 7 composition of Charge Stock B, was contacted with sulfided cobalt molybdate catalyst in a reactor of the following conditions:

Under the aforementioned operating conditions, the initial charge stock was completely hydrogenated as shown by Table 9.

TABLE 9 Charge Product Stock B (c) Bromine No 67. 0. 8 Bromine No. after M.A. Treat 48. 0 0.8 Wt. Basis of Feed to Vaporizer:

C O. 2 C 0. 6 0 Product- 99.0 Btms 1. 0

Total 100. 8

Volume Basis:

0 100. 0 101. 1 Btrn':

Total 100. 0 101. 1

14. 2 28. 7 26. 4 0. 3 9. 8 0. 3 5. 6 11. 0 Nanhthenes 8. 1 20. 2 Atom aties 51. 3 50. 7 Benzene 26. 0 25. 7 Tnlnene 15. l 14. 9 Xylenes 6. 8 8. 7 C Benzene 1.0 1. 3 C Benzene 0. 1 0. 1 C Benzene O. 3 Styrene 2. 0 Hydrogen Consumed, s. 446 Sulfur, Wt. percent Chg 0. 082 0. 0015 Percent Desuifnrimtirm 9 Existent Gum mg./100 m1 83. 8 1. 4 5 Hr. Potential Gum, mg./l00 ml. 2.197 10 1. 9 16 Hr. Potential Gum, mg./100 ml 3.177X10 3. 0

Example III Dripolene, Charge Stock B (Example 11), is charged to a vaporizer maintained at 360 F. and 600 p.s.i.g. Hot hydrogen recycle gas of 70 to 80 volume percent purity is employed to vaporize the charged dripolene. Based on an ASTM distillation of the vaporizer bottoms liquid, over 98% of the charge stock is vaporized.

The vaporized material, commingled dripolene and hydrogen-containing gas, is then contacted in a two-stage reactor over sulfided cobalt molybdate catalyst. Interstage cooling is accomplished by liquid quench, using a motor gasoline component tree of olefins and amounting to 14% of the charge.

The reactor pressure is maintained at 600 p.s.i.g., space rate is maintained between 2 to 3 vol./hr./vol. and a recycle hydrogen to oil mol ratio is 3. The initial inlet reactor temperature for each stage is 425 F.

Efiluent from the reactor after cooling is transmitted to a liquid gas separator. The liquid product from said separator, after stabilization, is blended with gasoline.

The product of this example, on a distilled (9;5+% overhead) and inhibited basis (5 lbs. N,N-di-sec-butyl- 8 p-phenylenediamine/ 1000 bbls.), has the following characteristics:

F1+3 cc. TEL Octane No. 101.0 Sulfur Content (wt. percent) 0.05

Obviously, many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

The invention claimed is:

1. The process for the selective hydrogenation of olefinic hydrocarbons of a dripolene charge stock in two reaction zones which consists essentially of vaporizing the charge stock With 700 to 1100 F. hydrogen containing gas, contacting the resulting vaporized mixture of charge stock and hydrogen containing gas in the first reaction zone with sulfided cobalt molybdate catalyst at a temperature between 300 to 900 F., adjusting the temperature of the efliluent from the first reaction zone before said eflluent enters a second reaction zone so that the reaction temperature in the second reaction zone is maintained below a maximum of 900 F. and contacting the temperature adjusted efiluent from the first reaction zone with sulfided cobalt molybdate catalyst in the second reaction zone.

2. The process of claim 1 wherein the inlet temperature of the charge to each reaction zone is between 400-800 F.

3. The method for selectively hydrogenating the olefinic hydrocarbons of a dripolene charge stock in two reaction zones wherein substantially none of the aromatic hydrocarbons in the charge stock are hydrogenated which consists essentially of vaporizing the charge stock with 7001100 F. hydrogen-containing gas, contacting the resulting vaporized mixture of charge stock and hydrogen-containing gas in the first reaction zone at a temperature between 300 to 900 F. with sulfided alumina supported catalyst containing a total of 8 to 18 percent by weight of the oxides of molybdenum and cobalt in the weight ratio of 4:1 to 5:1 molybdenum oxide to cobalt oxide, adjusting the temperature of the efliuent from the first reaction zone before said efliuent enters a second reaction zone so that the temperature in the second reaction zone is maintained below 900 F. and contacting in a second reaction zone the temperature adjusted efiluent from the first reaction zone with a sulfided. alumina supported catalyst containing a total of 8 to 18 percent by weight of the oxides of molybdenum and cobalt in the weight ratio of 4:1 to 5:1 molybdenum oxide to cobalt oxide.

4. The method of claim 3 wherein the hydrogen-com taining gas is composed of at least 25% hydrogen by volume.

References Cited by the Examiner UNITED STATES PATENTS 2,889,264 6/ 1959 Spurlock 208143 3,053,915 9/ 1962 King 208143 3,133,013 5/1964 Watkins 208-264 3,161,586 12/1964 Watkins 208264 DELBERT' E. GANTZ, Primary Examiner.

S. P. JONES, Assistant Examiner. 

1. THE PROCESS FOR THE SELECTIVE HYDROGENATION OF OLEFINIC HYDROCARBONS OF A DRIPOLLENE CHARGE STOCK IN TWO REACTION ZONES WHICH CONSISTS ESSENTIALLY OF VAPORIZING THE CHARGE STOCK WITH 700 TO 1100*F. HYDROGEN CONTAINING GAS, CONTACTING THE RESULTING VAPORIZED MIXTURE OF CHARGE STOCK AND HYDROGEN CONTAINING GAS IN THE FIRST REACTION ZONE WITH SULFIDED COBALT MOLYBDATE CATALYST AT A TEMPERATURE BETWEEN 300 TO 900*F., ADJUSTING THE TEMPERATURE OF THE EFFLUENT FROM THE FIRST REACTION ZONE BEFORE SAID EFFLUENT ENTERS A SECOND REACTION ZONE SO THAT THE REACTION TEMPERATURE IN THE SECOND REACTION ZONE IS MAINTAINED BELOW A MAXIMUM OF 900*F. AND CONTACTING THE TEMPERATURE ADJUSTED EFFLUENT FROM THE FIRST REACTION ZONE WITH SULFIDED COBALT MOLYBDATE CATALYST IN THE SECOND REACTION ZONE. 